1. Field
Example embodiments of the present invention relate to a cleaning solution, for example, a cleaning solution for cleaning a silicon surface; and methods for fabricating a semiconductor device using the same.
2. Description of the Related Art
A process of fabricating a semiconductor device may include an ion implantation process for forming an impurity diffusion layer, e.g., wells, and source/drain regions in a silicon substrate, a process of forming variously shaped structures by depositing or growing conductive or insulating thin films on the silicon substrate and patterning the conductive or insulating thin films, and a process of developing contacts to form circuits by electrically connecting stacked conductive structures to one another. The condition of the silicon surface exposed during each process may affect the quality of a thin film to be formed by subsequent processes. The exposed silicon surface may be deteriorated from contaminants or damages occurring during processes. That is, the exposed silicon surface may be damaged by various contaminants, for example, a native oxide layer, organic matters, metal impurities and particles and/or the like, during the preceding processes or while handling the silicon substrate between the processes. The exposed silicon surface may also be damaged during a dry etching process for patterning the thin films or during an ion implantation process for forming wells or sources/drains.
Thus, a cleaning process may be performed to remove a contamination source from the exposed silicon surface and a damaged portion of the silicon surface prior to each process. This cleaning process may need to be sufficiently performed prior to the processes sensitively affected by the condition of the silicon surface, for example, an epitaxial process, a salicide process and a self aligned contact (SAC) process and/or the like. In particular, the damaged portion of the exposed silicon surface may cause lattice defects on an epitaxial layer or a metal salicide layer and may increase surface roughness, and further it may increase leakage or resistance on contacts. Thus, the damaged portion may be sufficiently removed prior to each process.
In the conventional process of cleaning the silicon surface, standard clean 1 (SC1), which is a mixture of hydrogen peroxide (H2O2), ammonium hydroxide (NH4OH) and deionized water (DI water), or a dilute fluoric acid solution and/or the like may be used according to needs. However, it may be difficult to use the SC1 and the dilute fluoric acid, for a long time, due to-the low etch selectivity of silicon to a silicon oxide layer, specifically, a BPSG layer used as an interlayer insulating layer in a process of fabricating a semiconductor device. Consequently, it may be difficult to expect a satisfactory cleaning effect.